The present invention relates generally to flow control devices, and more particularly to devices, such as valves, which are well-suited for controlling the flow of liquids, gases, slurries, suspensions, mixtures and other fluid or fluidized streams, collectively referred to below as "fluids" or "media." Devices constructed in accordance with the present invention are especially well-suited for controlling the flow of a fluid or medium which is contaminated with, or which includes by design, sand, sediments, and/or other solid particulate matter having abrasive properties.
A variety of valves suitable for controlling the flow of liquid and gaseous fluids are available. Such valves typically incorporate sealing surfaces or elements which may include diaphragms, O-rings, pistons, disks or specially machined tapered seats. The ability of such devices to function properly when exposed to sediment, sand, dirt, metal chips or other particles in the fluid flow varies with specific design parameters and operating conditions, but in general is not good. Such contaminants tend to clog, score, or otherwise damage sealing surfaces in the valves, leading to degradations in performance, or outright failures, of the valves.
One particular application for valves in which the above problems have been identified relates to large, ocean going vessels, and particularly to navel warships. Warships are typically provided with sprinkler systems which are intended to dowse fires in or around the ship's magazine, fuel supply, and other installations. Such ships may also be provided with wash-down systems which are used in decontaminating surfaces which have been exposed to chemical clouds, radioactive fallout, or other hazards. Water to supply such systems is generally drawn from the sea through one or more large water inlets located below the water line of the ship. Sea water may also be drawn in through these or other inlets to provide water for use in maintenance, cooling and other applications where clean, fresh water is not required. Although these inlets may be provided with strainers to keep out seaweed and other large objects, sand, sediments, and other smaller contaminants are often drawn into these systems. This is particularly true when the ship is required to sail or dock in relatively shallow waters or harbors.
Accordingly, a need exists for valves which can control the flow of media which may be contaminated with sand, sediments, or other solid particulate matter. It is an object of the present invention to provide such valves.
Another object of the present invention is to provide a flow control device which is relatively simple and inexpensive to manufacture and maintain, and which is very reliable in operation.
Yet another object of the present invention is to provide a flow control device which is suitable for use in a fire control system, and which is provided with a feature which allows the device to automatically open or operate when the temperature of the device increases beyond a predetermined temperature value.
These and other objects of the present invention are attained in a flow control device which comprises a body having side walls which define a fluid holding chamber, at least one inlet opening into the chamber, at least one outlet opening into the chamber and having an outlet opening in the valve body, collapsible tubing means sealingly attached to the outlet opening and extending into the chamber, and means for selectively collapsing and uncollapsing the tubing means to block and unblock the flow of fluid from the chamber through the outlet opening. The means for collapsing the tubing means preferably comprises a mechanical device disposed adjacent the tubing means at a first location spaced apart from the side walls of the chamber. The fluid or media flow enters the chamber under a positive pressure. When the mechanical device collapses the tubing at the first location, the pressure of the surrounding fluid in the chamber exerts a collapsing force on that portion of an outer surface of the tubing means between the mechanical device and the side wall of the chamber, causing that portion of the tubing means to collapse. The mechanical device may comprise a camming device and an operator for the camming device, such as a handle and a shaft which extends through the side wall of the chamber. In one embodiment, the valve includes at least two outlets, each having collapsible tubing means attached thereto. In this embodiment, both tubing means are commonly collapsed by operation of a single camming device.
One embodiment of the mechanical device further includes a pair of closure members oppositely disposed on either side of the tubing means. At least one of the members is movably mounted and situated adjacent a camming surface of the camming device. The movable members cooperate with the camming device to collapse the tubing means when the camming device is operated.
One means for uncollapsing the tubing means comprises pressure exerted by the fluid or media on an inner surface of the tubing means. When the mechanical device is moved to a position which does not collapse the tubing means at the first location, the pressure of the fluid or media in the chamber causes the tubing means to return to an uncollapsed (open) condition. The tubing means may be formed from a natural or synthetic rubber, or a functionally equivalent material, having a durometer hardness rating which is selected on the basis of at least one characteristic (such as specific gravity, viscosity, etc.) of a fluid flow controlled by the device. In one embodiment, the hardness rating is selected for the sizes and types of particulate matter expected in the fluid flow. In one application involving a sand and sediment contaminated flow of water, tubing formed of a synthetic rubber, marketed under the name VITON and having a durometer hardness rating in the range of 60-90 was found acceptable. Proper selection of the material and hardness rating assures that the tubing means will adequately surround and encapsulate particles which may be carried by particular media flows, and that an undue amount of force or pressure will not be required to collapse the tubing.
Devices which utilize the present invention may further comprise means responsive to an increase in temperature for automatically returning the tubing means to an uncollapsed state to allow fluid to flow from the chamber through the outlet means when the temperature of the device increases beyond a predetermined value. The means responsive to an increase in temperature may incorporate a metal (or other material) having a relatively low melting point which corresponds to the selected predetermined value. In one embodiment of the invention, the means for selectively collapsing the tubing means includes a movably mounted member disposed adjacent the tubing means, biasing means for urging the member against the tubing means to collapse the tubing and block the flow of fluid from the chamber, and means for selectively moving the member against the biasing means and away from the tubing means to allow the tube to return to an uncollapsed state so that fluid may flow from the chamber through the outlet means. In this embodiment, the low melting point metal forms a supporting base for the biasing means (e.g., a coil spring) such that when the temperature of the device increases beyond the predetermined value, the supporting base for the biasing means melts and the biasing means sinks into the base and ceases to urge the member against the tubing means. This allows the tubing to return to the uncollapsed state so that fluid may flow from the chamber through the associated outlet.
In another embodiment of the invention, an improved means for automatically opening the valve when it is exposed to a temperature which reaches or exceeds a predetermined temperature is provided. The valve has two portions which define two valve chambers. An inlet, which is coupled to a source of pressurized fluid, opens into one of the valve chambers and an outlet coupled to downstream devices opens into the other valve chamber. A piece of collapsible tubing couples the two valve chambers. A shaft extends into the valve and is provided with a mechanism for pinching the collapsible tubing shut which causes the collapsible tubing to collapse due to the pressure exerted on its exterior by the pressurized fluid surrounding it. A coil spring is attached to the shaft and the valve body. When the valve is closed, i.e., the collapsible tubing collapsed, the coil spring is biased to cause the shaft to rotate if released. The shaft is prevented from rotating by a fusible link. When the temperature reaches or exceeds a predetermined temperature, the fusible link melts. This releases the shaft and the coil spring rotates the shaft which permits the collapsible tubing to uncollapse, thus opening the valve.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.